The present invention relates to therapeutic compositions for treating nasal passages. In particular, the present invention relates to decongesting and moisturizing the tissues that line nasal passages.
The nose is a very specialized and complicated structure that serves dual functions as the organ for the sense of smell and as an entry to the respiratory tract. As part of the respiratory tract, a healthy nose moisturizes and warms incoming air and filters out foreign materials.
Nasal passages and other portions of the respiratory tract are lined with specialized tissue layers. In the nose and sinus areas this tissue is often called the nasal mucosa. Like many tissues, the nasal mucosa is composed of several cell layers and cell types. Mucous cells are one type of cell found in the nasal mucosa. These cells are found throughout the nasal mucosa and are generally clustered into small glands. These glands secrete a sticky substance called mucus. Mucus is composed of water, shed epithelial (surface) cells, dead leukocytes, mucin, and inorganic salts, among other things, that are all held in suspension. Mucus functions as a trap for airborne particles (e.g., dust, bacteria, and viruses) that enter the nasal passages. Mucus also lubricates the walls of the nose, sinuses, and throat.
In a healthy nose, the mucus is cleared from the nasal passages on a regular basis by a layer of cells in the nasal mucosa called the ciliated columnar epithelium. These cells possess small hair-like projections called cilia that undulate and xe2x80x9csweepxe2x80x9d mucus through the nasal passages allowing it to drain to the back of the throat where it can be swallowed or expelled. This line of defense protects the body against the bacteria and viruses that continually enter the nose and mouth.
Connected to the nose are sinuses or air-filled cavities located behind certain facial bones. There are four groups of sinuses, namely, frontal, sphenoidal, ethmoidal, and maxillary. The sinuses are also lined with mucus secreting tissue. The sinuses are normally kept clear when mucus drains through them into the nasal passages. If they are obstructed for any reason, such as from the congestion present during a cold, normal drainage may not occur and infection of the sinuses may result.
Virtually all persons are occasionally stricken with acute upper respiratory infections (common colds), acute or chronic allergy flare-ups of the nose, and/or acute or chronic non-allergic rhinosinusitis. Persons afflicted by such conditions usually incur significant discomfort and inconvenience.
All of these disorders are characterized by intense inflammation of the nasal mucosa. A number of symptoms contribute to the discomfort and inconvenience associated with the common cold or sinusitis. Symptoms often include one or more of the following: nasal congestion, post-nasal drip, decreased sense of smell, ear fullness, headache, sore throat, malaise, muscle and joint aches, fatigue, cough, chest congestion, fever, chills and gastrointestinal maladies. Considerable research has been conducted over the years aimed at reducing the incidence and duration of symptoms associated with allergies and common colds.
Perhaps the most common symptom experienced by cold and allergy sufferers is xe2x80x9ccongestion.xe2x80x9d The term xe2x80x9ccongestionxe2x80x9d is commonly used by the layperson and in the patent literature as catch-all term to describe a complex series of events that hinder a person""s ability to breathe through the nose when they have a cold, sinusitis or an allergic reaction.
For example, xe2x80x9ccongestionxe2x80x9d can include a physiological response to an irritant that involves increased blood flow to tissues lining the nose. This increased blood flow causes these tissues to swell and physically block the nasal passages. Alternatively, when a nose is irritated or injured, fluid can seep into the free spaces in the tissues of the nose or build up in individual cells thereby causing additional xe2x80x9ccongestionxe2x80x9d. xe2x80x9cCongestionxe2x80x9d can also include the overproduction of mucus or the buildup of mucus due to increased mucus viscosity or depressed cilia activity or both. xe2x80x9cCongestionxe2x80x9d may also occur when a person lies on his or her side causing receptor cells in the nose to close off one nasal airway. Changes in temperature and/or humidity can alter the tissue of the nose and cause a xe2x80x9ccongestedxe2x80x9d feeling.
Current medications and treatments for xe2x80x9ccongestionxe2x80x9d provide only minimal symptom relief and some have undesirable side effects. Over-the-counter medications containing antihistamines sometimes cause drowsiness and impair cognitive judgment so that driving an automobile or operating other power driven machinery can be dangerous. Decongestants and adrenalin derivatives can elevate blood pressure, cause heart palpitations and stimulate brain activity causing insomnia or hyperalertness.
Numerous over-the-counter sprays (e.g., Afrin(copyright)) relieve some symptoms, but contain active ingredients such as the vasoconstrictor oxymetazoline hydrochoride. These types of sprays are directed at reducing swelling caused by increased blood flow to the nasal mucosa and are quite effective. Unfortunately, they are also associated with a significant addictive, rebound phenomenon of the nasal membranes (Rhinitis Medicamentosa). As a result, over-the-counter sprays with these types of active ingredients may actually lengthen the duration of common cold or sinusitis symptoms.
Inhaled corticosteroid nasal sprays provide some relief for allergic rhinitis but do not reduce inflammation caused by acute viral infections, or inflammation associated with other forms of non-allergic rhinitis (atrophic rhinitis, vasomotor rhinitis, hormonally-induced vasomotor instability, etc.). Prolonged use of steroid sprays has also been associated with drying, cracking and bleeding of the nose.
More passive treatments such as isotonic saline mists are also widely marketed for purposes of moisturizing the nose and relieving cold and allergy symptoms. Several patents discuss herbal based mists as an alternative to over-the-counter sprays such as Afrin(copyright).
These more passive sprays and treatments have proved to be less than satisfactory at providing the relief sought by sufferers of colds or allergies or other nasal problems. For example, isotonic saline mists add moisture to the nose but provide little overall relief for congestion.
Accordingly, a need exists for a nasal spray that provides a noticeable measure of relief for those that suffer from xe2x80x9ccongestionxe2x80x9d of the nasal passages yet does not exhibit the harmful side effects associated with sprays that contain active ingredients such as vasoconstrictors and steroids. Such a spray should be economical to produce and safe for use by most individuals suffering from xe2x80x9ccongestion.xe2x80x9d
In view of the foregoing discussion, an object of the invention is to provide a nasal spray that eases congestion of the nasal passages, in particular, congestion due to decreased ciliary function, swelling, fluid retention, increased mucus secretion and/or mucus buildup.
A further object of the invention is to provide a method for manufacturing such a nasal spray. A still further object of the invention is to provide method of treating the nasal passages, in particular the nasal mucosa, to ease the discomfort associated with congestion due to decreased ciliary function, swelling, fluid retention, increased mucus secretion and/or mucus buildup.
The invention meets these and other objects by providing a composition for osmotic decongestion and moisturization of the nasal passages comprising water, a ciliary stimulant, a mucus thinning agent, an osmotic agent, glycerin, and a preservative. Preferably the composition is alkaline and is hypertonic with respect to the cells of the nasal mucosa.
The invention also meets the above stated objects by providing a method of preparing an alkaline, hypertonic composition for use in osmotic decongestion of the nasal passages. The method comprises obtaining a quantity of water that is between about 67% and 68% of the total composition by volume; adding a quantity of a ciliary stimulant that is between about 4% and 5% of the total composition by volume; adding a quantity of a mucus thinning agent that is about 20% of the total composition by volume; adding a quantity of an osmotic agent that is between about 3% and 4% of the total composition by volume; adding a quantity of glycerin that is about 5% of the total composition by volume; adding less than 1% by volume of a preservative; and stirring the composition to ensure thorough mixing. The method may also comprise adjusting the pH of the composition to between 7.5 and 8.5 and packaging the composition for use as a nasal spray by individuals.
The invention also provides a method of relieving congestion of the nasal mucosa consisting of removing fluid from the nasal mucosa through osmosis by the application of a hypertonic solution comprising sugar, thinning the mucus present in the nose by the application of an alkaline solution; and stimulating ciliary function by application of a saline solution wherein the steps of removing fluid, thinning mucus and stimulating ciliary function are all physiological responses to the application of a single hypertonic, alkaline composition comprising a sugar solution, an alkaline solution and a saline solution.
As mentioned previously, the term xe2x80x9ccongestionxe2x80x9d is often used to describe a combination of physiological responses that result in clogged nasal passages and sinuses. Many of the known nasal sprays concentrate on the reduction of blood flow to the nasal mucosa through use of vasoconstrictors. These sprays are typically formulated to maximize the benefit of the vasoconstrictors and provide little or no therapeutic action in regard to the other causes of nasal congestion. Other, more passive sprays, lubricate or moisten the nose but provide little relief in the way of decongestion.
In contrast, the present invention is a hypertonic, alkaline nasal spray that avoids the use of vasoconstrictors and aids in the decongesting and moisturizing of the nose through osmotic activity, thinning and decreasing the viscosity of mucus, and increasing ciliary function.
For purposes of this discussion, osmosis may be defined as the spontaneous passage or diffusion of water through a semipermeable membrane (one that blocks the passage of dissolved substances) from an area of higher water concentration to an area of lower water concentration. Stated alternatively, water will diffuse down its concentration gradient or into a hypertonic environment to achieve a state of equilibrium. The semipermeable membranes at issue here are the tissues of the nasal mucosa and even the plasma membranes of individual cells within the tissues.
In one embodiment, the spray according to the invention is a composition for inducing osmotic decongestion of nasal passages. The composition also lubricates and moisturizes the nose and thins mucus. The composition is comprised primarily of water and other passive components.
One component of the composition is a ciliary stimulant. As noted previously, the action of cilia in cells of the nasal mucosa is important in keeping the nasal passages clear of mucus. If cilia function is subnormal, mucus will build up and contribute to congestion of the nasal passages.
Saline solutions provide a physiological stimulant for ciliary activity. Saline solutions are relatively inexpensive and are simple to prepare. Accordingly, in a preferred embodiment of the invention the ciliary stimulant is a saline solution that is between 23% and 24% sodium chloride (i.e., 23 mg NaCl/ml water). In a more preferred embodiment the saline solution is a 23.4% solution of sodium chloride.
Another component of the composition according to the invention is a mucus thinning agent. As used herein, the term mucus thinning agent is defined as an agent, other than water, that lowers the viscosity of the mucus thereby making it more susceptible to transport by the cilia. For example, mucus derives its name from the substance mucin, which is secreted as part of the mucus. Mucins are high molecular weight glycoproteins with an oily texture that provide protection and lubricating functions. Mucin is a fairly viscous substance and adds to the viscosity of mucus. The viscosity of mucin, and in turn that of mucus, can be altered by a change in pH. The higher the pH, the less viscous the mucin.
Accordingly, in preferred embodiments the mucus thinning agent utilized in the practice of the invention is an alkaline agent, in particular, an about 8% to about 9% solution of sodium bicarbonate and water (e.g., 8 mg NaHCO3/ml water). In more preferred embodiments the sodium bicarbonate solution is about 8.4%.
As noted above, the composition according to the invention uses osmosis to aid in the decongestion of the nasal passages. In general terms, the osmotic effect utilized in the present invention can be described as follows: by bathing the nasal mucosa in a hypertonic solution, osmotic forces will drive (or pull) water from the free spaces in the nasal mucosa tissue and from the intracellular environment into the nasal passages thereby shrinking the nasal mucosa and providing extra fluid for moisturizing the nose and transportation of the mucus from the nasal passages.
This osmotic effect requires that the composition be hypertonic with respect to the nasal mucosa. Although all of the components present in the composition contribute to the hypertonicity of the composition, as used herein the term osmotic agent refers to an agent specifically added to the composition to increase the solute level in the composition and contribute to achieving hypertonicity of the spray. In preferred embodiments the osmotic agent used in the practice of the invention is a sugar selected from the group comprising monosaccharides and disaccharides. Sugars such as glucose, sucrose and fructose are preferred with sucrose being especially preferred.
The osmotic agent utilized in the practice of the invention is preferably an 85% solution of a sugar, preferably sucrose, and water.
Another aspect of the invention is to increase the moisture and lubrication inside the nose. During colds or allergic responses, the inside of the nose can become irritated and dry due to natural forces or in response to medications. Some people naturally have a dry nose which can lead to cracking and scaling within the nose. The composition according to the invention addresses these issues by including glycerin as a moisturizer and lubricant. The glycerin also aids in achieving the hypertonic nature of the composition. Preferably the glycerin is U.S.P. grade (99.5%).
As noted previously, the composition preferably has an alkaline pH to lower the viscosity of mucus. In preferred embodiments the pH of the composition is between about 7.5 and 8.5, most preferably around 8. The incorporation of the above discussed mucus thinning agent will usually ensure that the composition is alkaline in nature. If downward pH adjustment is required the addition of small amounts of an acid can be used to achieve a pH of about 8. Any physiological acceptable acid may be used. A 10% hydrochloric acid solution has been used in test samples and provides acceptable results. In the unlikely event upward pH adjustment is necessary, additional sodium bicarbonate may be used.
A preservative should also be used to maintain the integrity of the composition. Suitable preservatives are well known to those skilled in the art. In preferred embodiments, however, a small quantity (e.g., less than 1% by volume) of potassium sorbate is added to the composition.
The preferred relative amounts of each of the above components in the total composition can be summarized as follows: between about 67% and 68% water; between about 4% and 5% of the ciliary stimulant; between about 3% and 4% of the osmotic agent; about 5% glycerin; about 20% of the mucus thinning agent; less than 1% of a preservative; and a small quantity of a pH adjusting agent if needed.
The composition according to the invention is most efficiently made in stepwise fashion by adding and mixing the components with sterile water. In a preferred embodiment the method comprises preparing a composition that is between about 67% and 68% water and adding to the water a 23% to 24% saline solution that is between about 4% and 5% of the total composition by volume. To this is added a quantity of an 85% sugar solution that equals between about 3% and 4% of the total composition by volume.
The method further comprises adding a quantity of glycerin such that it is about 5% of the total composition by volume.
Next, a quantity of 8% to 9% sodium bicarbonate solution is added such that the quantity is about 20% of the total composition by volume.
Lastly, add about 1 ml of a 100 mg/ml potassium sorbate U.S.P. solution and mix thoroughly. Small amounts of 10% hydrochloric acid or additional sodium bicarbonate may be added to achieve a pH of between about 7.5 and 8.5.